The present invention is an improvement which may be applied to known wire bonding equipment (or new wire bonding equipment) such as the Maxμm™ automatic wire bonder available from Kulicke and Soffa Industries, Inc. of Willow Grove, Pa. Such wire bonding equipment typically includes a material handling system which operates to supply and remove work pieces, or lead frames, to a bonding station having an indexer. During the wire bonding process, the indexer moves each lead frame relative to a bonding head element of the wire bonder.
In conventional wire bonding equipment, the material handling system typically includes at least one magazine handler which holds a stack of lead frames. Lead frames move sequentially from the magazine handler to the bonding station along a support structure including, for example, a pair of rails. The wire bonding process is performed with the lead frame positioned at the bonding station. Following completion of the wire bonding process, the lead frame may be returned to the magazine handler.
Typically, each lead frame is pre-heated prior to the wire bonding process. The preheat process is typically performed with a pre-heat block positioned intermediate the magazine handler and the bonding station. The lead frame is brought into contact with the pre-heat block, and is heated to a temperature of, for example, approximately 160 degrees C. (320 degrees F.). For example, the pre-heat process may take approximately 15 seconds to complete.
In a conventional wire bonder having a single magazine handler, the pre-heat and wire bonding operations are typically performed sequentially, and thus the total processing time for a single lead frame includes both the time for the pre-heat operation and the time for the wire bonding process (which, depending on the number of connections to be formed and the speed of the wire bonding equipment, can vary, for example, over the range of about 37 seconds to about 120 seconds). If it were possible to perform all or part of the pre-heat operation on a first lead frame while simultaneously a second lead frame undergoes the bonding operation, it would be possible to increase the total number of lead frames processed by the wire bonder in a given period of time. However, in conventional wire bonders having a single magazine handler, the return path from the bonding station to the magazine handler (along which the pre-heat block is positioned) is desirably kept clear to allow a lead frame which has completed the wire bonding process to move from the bonding station to the magazine handler without the obstruction of a second lead frame undergoing the pre-heat process. Thus, the pre-heating and wire bonding processes are performed sequentially. It is known to provide two magazine holders with the wire bonder, allowing a first lead frame from the first wire bonder to be pre-heated, while a previously pre-heated second lead frame undergoes the wire bonding process. It would be desirable, however, to provide the improved processing times associated with two magazine holders without incurring the additional cost of a second magazine holder.